Determination of ⁹⁰Sr and ²¹⁰Pb in food samples by liquid scintillation counting after sequential separation with an...

⁹⁰Sr and ²¹⁰Pb are considered to be key radionuclides in internal exposure resulting from dietary intake, however, the established methods employed for their detection are time-comsuming. A method for the sequential separation of ⁹⁰Sr and ²¹⁰Pb using a Sr·spec resin by LSC measurement is developed, which is highly suitable for food safety monitoring as its minimal sample requirements. The sequential separation of Sr and Pb from the sample was using 0.05 mol/L HNO₃ and 0.05 mol/L C₆H₅O₇(NH₄)₃. The chemical recoveries of Sr and Pb measured using ICP-OES were 72-83% and 80-88%, respectively. The minimum detectable activities of ⁹⁰Sr and ²¹⁰Pb in the food sample were 36.2 mBq/kg and 28.6 mBq/kg, respectively, obtained from a 0.1 kg fresh sample and 300 min counting time. The method was validated using reference materials and compared with other methods. The feasibility of the developed method for other highly complex food matrices needs further investigation.